The terrestrial shallow seismic reflection technique applied to the characterization and assessment of shallow sedimentary environments

Terrestrial shallow seismic reflection offers great potential in the characterization of shallow sedimentary environments. Experience from the oil industry9s standard use of the seismic technique in basin-wide, 3D seismic stratigraphic studies reinforces this point. Unlike the marine environment, where it is relatively easy to record high resolution shallow reflections, land acquisition can be affected by near surface layers that absorb the high frequency signals necessary to resolve thin sub-surface sedimentary layers. The quality of reflection data recorded in shallow terrestrial environments can be difficult to predict without initial field trials. Shallow 2D and 3D reflection data can be improved greatly by the use of appropriate seismic sources, receivers and modern distributed recording systems utilizing many recording channels. UK-based case studies are described at Porth Neigwl; Dinas Dinlle; St Bees and Camlad Valley where the resolution capabilities of the reflection data are of the same magnitude as the thickness of sedimentary units exposed in cliff section or boreholes. At these sites, a fully integrated interpretation framework for sedimentary environments can be determined. A survey at Llanrhidian Marsh, Gower is also described where organic rich surface sediments absorbed the high frequency reflections necessary to image the thin sedimentary units revealed in shallow boreholes.